High-pressure processing chamber for a semiconductor wafer

Abstract

A processing chamber having an improved sealing means is disclosed. The processing chamber comprises a lower element, an upper element, and a seal energizer. The seal energizer is configured to maintain the upper element against the lower element to maintain a processing volume. The seal energizer is further configured to generate a sealing pressure in a seal-energizing cavity that varies non-linearly with a processing pressure generated within the processing volume. In one embodiment, the seal energizer is configured to minimize a non-negative net force against one of the upper element and the lower element above a threshold value. The net force follows the equation P 2 *A 2 −P 1 *A 1 , where P 2 equals the sealing pressure, P 1 equals the processing pressure, A 2 equals a cross-sectional area of the seal-energizing cavity, and A 1 equals a cross-sectional area of the processing volume.

The invention claimed is: 
     
       1. An apparatus for processing a semiconductor wafer, comprising:
 a. an upper element; 
 b. a lower element, wherein the upper element and the lower element are configured to be brought together to form a processing volume; 
 c. a seal energizer that comprises a seal-energizing cavity coupled to the upper element and configured to maintain the upper element against the lower element by a sealing pressure generated within the seal-energizing cavity; and 
 d. a pressure controller configured to automatically non-linearly vary the sealing pressure to lag a processing pressure generated within the processing volume and maintain the processing volume during processing. 
 
     
     
       2. The apparatus of  claim 1 , wherein the seal energizer is configured to apply a non-negative net force against one of the upper element and the lower element above a threshold value, the net force following the equation P 2 *A 2 −P 1 *A 1 , wherein P 2  equals the sealing pressure, P 1  equals a pressure generated within the processing volume, A 2  equals a cross-sectional area of the seal-energizing cavity, and A 1  equals a cross-sectional area of the processing volume. 
     
     
       3. The apparatus of  claim 2 , wherein the cross-sectional area A 2  is larger than the cross-sectional area A 1 . 
     
     
       4. The apparatus of  claim 1 , wherein the seal energizer further comprises a first cavity, wherein the first cavity is coupled to the seal-energizing cavity, and the seal energizer is configured so that a first pressure generated within the first cavity generates a second pressure in the seal-energizing cavity larger than the first pressure. 
     
     
       5. The apparatus of  claim 1 , further comprising a means for generating supercritical conditions coupled to the processing volume. 
     
     
       6. The apparatus of  claim 5 , further comprising a CO 2  supply vessel coupled to the processing volume. 
     
     
       7. The apparatus of  claim 1 , wherein the upper element and the lower element form a supercritical processing chamber. 
     
     
       8. The apparatus of  claim 1 , wherein the seal energizer comprises a hydraulic piston coupled to the lower element and configured to maintain the processing volume. 
     
     
       9. The apparatus of  claim 1 , wherein the pressure controller is programmed to maintain a difference between a sealing force and a force generated within the processing volume within a preselected range. 
     
     
       10. The apparatus of  claim 9 , wherein a lower bound of the preselected range includes a minimum force for maintaining the processing volume. 
     
     
       11. The apparatus of  claim 10 , wherein the minimum force is based on a delay between generating the sealing force and generating the force within the processing volume. 
     
     
       12. The apparatus of  claim 1 , wherein the force generated within the processing volume varies during a processing cycle. 
     
     
       13. The apparatus of  claim 1 , wherein the pressure controller comprises a pressure regulator. 
     
     
       14. The apparatus of  claim 13 , further comprising a pressure monitor coupled to the processing volume and to the pressure regulator. 
     
     
       15. An apparatus for processing a semiconductor wafer, comprising:
 a. an upper element; 
 b. a lower element coupled to a seal-energizing cavity, wherein the upper element and the lower element are configured to be brought together to form a processing volume; and 
 c. means for automatically non-linearly varying a sealing pressure within the seal-energizing cavity to maintain within a preselected range a difference between a sealing force and a force generated within the processing volume, thereby maintaining the processing volume. 
 
     
     
       16. An apparatus for processing a semiconductor wafer, comprising:
 a. a processing chamber comprising a processing volume for processing the semiconductor wafer by generating a processing pressure; and 
 b. means for maintaining the processing volume by sensing the processing pressure during processing and automatically generating a sealing pressure that non-linearly lags the sensed processing pressure.